package com.ncu.cloundeoffice.config.jwt;

import io.jsonwebtoken.Claims;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.SignatureAlgorithm;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.stereotype.Component;

import java.util.Date;
import java.util.HashMap;
import java.util.Map;

/**
 *JwtToken工具类
 */
@Component
public class JwtTokenUtil {


    //荷载claim的名称
    private static final String CLAIM_KEY_USERNAME= "sub";

    //荷载的创建时间
    private static final String CLAIM_KEY_CREATED= "created";

    //jwt令牌的密钥
    @Value("${jwt.secret}")
    private String secret;

    //jwt的实效时间
    @Value("${jwt.expiration}")
    private Long expiration;


    /**
     * 根据用户信息生成token
     * @param userDetails
     * @return
     */
    public String generateToken(UserDetails userDetails){
        Map<String ,Object> claims = new HashMap<>();
        claims.put(CLAIM_KEY_USERNAME,userDetails.getUsername());
        claims.put(CLAIM_KEY_CREATED,new Date());
        return generateToken(claims);
    }

    /**
     * 从token获取用户信息
     * @param token
     * @return
     */
    public String getUserNameFromToken(String token){
        String username = null;
        Claims claims = getClaimsFromToken(token);
        try {
            username = claims.getSubject();
        }catch (Exception e){
            username = null;
        }
        return username;
    }

    /**
     * token是否有效
     * @param token
     * @param userDetails
     * @return
     */
    public Boolean validateToken(String token, UserDetails userDetails){
        String username = getUserNameFromToken(token);
        return username.equals(userDetails.getUsername()) && !isTokenExpired(token);
    }

    /**
     * 是否可以刷新
     * @param token
     * @return
     */
    public Boolean canRefresh(String token){
        return !isTokenExpired(token);
    }

    /**
     * 刷新token
     * @param token
     * @return
     */
    public String refreshToken(String token){
        Claims claims = getClaimsFromToken(token);
        claims.put(CLAIM_KEY_CREATED,new Date());
        return generateToken(claims);
    }

    /**
     * 判断token是否失效
     * @param token
     * @return
     */
    private boolean isTokenExpired(String token) {
        Date expireDate = getExpiredDateFromToken(token);
        return expireDate.before(new Date());
    }

    /**
     * 从token中获取失效时间
     * @param token
     * @return
     */
    private Date getExpiredDateFromToken(String token) {
        Claims claims = getClaimsFromToken(token);
        return claims.getExpiration();
    }

    /**
     * 根据token获取荷载
     * @param token
     * @return
     */
    private Claims getClaimsFromToken(String token) {
        Claims claims = null;
        try{
            claims = Jwts.parser()
                    .setSigningKey(secret)
                    .parseClaimsJws(token)
                    .getBody();
        }catch (Exception e){
            e.printStackTrace();
        }
        return claims;
    }


    /**
     * 格局荷载生成JWTToken
     * @param claims
     * @return
     */
    private String generateToken(Map<String ,Object> claims){
        return Jwts.builder()
                .setClaims(claims)
                .setExpiration(generateExpiration())
                .signWith(SignatureAlgorithm.HS512,secret)
                .compact();
    }

    /**
     * 生成token实效时间
     * @return
     */
    private Date generateExpiration() {
        // 当前时间+配置时间
        return new Date(System.currentTimeMillis() + expiration* 1000) ;
    }


}
